In general, mobile communication systems have been developed to provide voice services while guaranteeing user mobility. Such mobile communication systems have gradually expanded their coverage from voice services through data services up to high-speed data services. However, as current mobile communication systems suffer resource shortages and users demand even higher-speed services, development of more advanced mobile communication systems is needed.
Meanwhile, dual connectivity enables a user equipment (UE) to connect to two different base stations (ENBs) and to receive services therefrom at the same time. For example, a dual connectivity enabled UE may connect to macro and small ENBs having different functions and receive services therefrom.
Standardization bodies for communication are currently active to investigate various technologies for dual connectivity. In particular, it is crucially necessary to develop a scheme for determining connection configuration between UE and ENB and for handling handover.